The present invention relates generally to wall structures constructed from hardenable material, such as concrete. In particular, the present invention relates to concrete walls that are constructed from form liners which can be placed next to one another to form a wall surface which resembles a wall made from stones.
Wall structures can be constructed from a single uniform building material such as concrete or drywall, or from unique individual building materials such as natural stones, cut stones, or bricks that are bonded together with an adhesive substance, such as mortar. When a continuous wall structure is formed from a uniform building material, the surface of the wall will typically have a smooth surface. By contrast, when a continuous wall structure is formed by arranging individual building materials relative to each other and maintaining them in place with an adhesive substance, the surface of the wall can have a random pattern, which may be more pleasing to the eye.
Although a wall comprised of individual stones may be desirable, building such a wall is not always a practical option. Constructing a wall made of stone is often labor intensive and requires highly skilled laborers. Specialized equipment and tools may also be required. In addition, the costs of the materials themselves are high, and the cost of the labor involved is likewise high.
An alternative to constructing a wall from natural or cut stones is to construct a wall using a moldable building material, such as concrete. Using concrete, a simulated stone wall can be created such that the surface of the wall looks as though the wall was built using individual stones. This can be accomplished by utilizing a system of forms and form liners placed inside a concrete form. The form liners are created with a reverse impression of a random pattern of stones and mortar. The concrete is poured into the form and is allowed to harden. After the concrete material hardens, the forms and form liners are removed to reveal a simulated stone wall.
Concrete is a particularly suitable material for building simulated stone walls because it results in a more realistic texture and feel, and resembles stone more than other types of building materials. However, forming a simulated stone wall using several form liners to create the stone pattern has been impractical to date. To get a more realistic, random appearance of stones, a large number of form liners may be needed. In addition, it is difficult to mask the joint created where adjacent form liners meet, which may result in the ability to determine the location of each form liner on the finished wall, which in turn makes the wall more obviously simulated rather than realistic.
In forming the simulated stone wall, it is typical in the field to use multiple form liners in an attempt to make a more realistic wall. A more random pattern can be achieved by increasing the number of form liners used in the wall when each form liner creates a different pattern of stones. However, the greater the number of form liners required to achieve a random appearance, the greater the cost of the finished wall. In an effort to reduce cost, it is desirable to design the form liners so that fewer form liner patterns are required, and the form liners can be repeated along the length of the wall while still achieving a random pattern.
Two problems are frequently encountered when a form liner is repeated in a continuous structure. The first problem arises due to the manner in which the form liners are arranged next to each other on the form. When individual form liners having generally linear sides are positioned adjacent to one another, it may become possible for the human eye to identify the joint created by the form liners in the finished wall. This is particularly true when the shape of the form liner is a simple shape, such as a rectangle. In addition, horizontal and vertical lines created in the stone pattern by the locations where the form liners are arranged are often more visible when the wall structure is viewed from an angle.
In an effort to reduce the visibility of lines in the resulting wall structure caused by the location of where the form liners are arranged next to one another, form liner systems have been developed which vary the outer shape of the form liner. Rather than making the form liner a simple a rectangular shape, the shape of the form liner is modified along its horizontal side, vertical side, or both by increasing the number of sides of the form liner. In addition, the angle at which the sides of the form liner intersect one another may also be varied. Such multi-sided form liners increases the complexity of manufacturing the wall, because the form liners must be carefully arranged on the form to ensure they fit next to each other properly and in the most efficient manner.
A second problem arises because the human eye is proficient at identifying repeating patterns. When a limited number of form liners are used to create a wall, individual shapes and patterns may be more easily discerned. This problem is particularly true of simulated natural and cut stone walls because in a real stone wall, every stone surface is unique. As a result, in making a simulated stone wall, if one of the form liners has a particularly distinctive stone, that stone may be more noticeable to the human eye if it appears more than once in the resulting wall.
Some multiple-sided form liners are designed so that the form liner can be rotated when it is placed adjacent another form liner on the form. The ability to rotate the form liner and still fit it to an adjacent form liner reduces the number of form liners required to obtain a suitably random appearing wall because merely inverting the stones makes them much more difficult for the human eye to recognize even when the pattern is repeated. This in turn reduces the cost of the resulting wall, and reduces the complexity of placing the form liners on the wall. However, such form liners may still result in obvious horizontal or vertical joint locations, and may only minimize, rather than eliminate, the ability to recognize repeating patterns in the finished wall.
Thus, there is a need in the art for a form liner that when properly arranged into a form liner system simulates a stone wall having a random appearance with no discernable horizontal or vertical lines or repeating patterns.